1. Field of the Invention
The present invention relates to a dust cover which is installed to a ball joint of a steering device in a vehicle.
2. Description of the Conventional Art
As a dust cover which is installed to a ball joint of a steering device in the vehicle, a structure as shown in FIG. 13 has been conventionally known.
More specifically, this kind of dust cover 100 is formed by a rubber-like elastic material (a rubber material or a synthetic resin material having a rubber-like elasticity), and is provided with a relatively large-diameter housing side attaching portion 101 which is fastened and fixed to an outer periphery of a housing 201 retaining a socket 202 of a ball joint 200 by a snap ring 104, a relatively small-diameter shaft side attaching portion 102 which is brought into close contact with a knuckle 204 fixed to a shaft portion 203b of a ball stud 203 in the ball joint 200 and is closely fitted and fixed to an outer periphery of the shaft portion 203b, and a tubular flexible film portion 103 which connects between the housing side attaching portion 101 and the shaft side attaching portion 102. A reinforcing ring 102a is buried in the shaft side attaching portion 102, the reinforcing ring 102a being provided for enhancing a close contact performance with the shaft portion 203b of the ball stud 203 and made of a synthetic resin.
This kind of dust cover 100 prevents a grease (not shown) which is filled at an appropriate amount in an inside space S from flowing out toward an external portion, prevents dusts from entering into a fitting portion between the socket 202 and a spherical end portion 203a of the ball stud 203 from the external portion, and is structured such that the flexible film portion 103 freely deforms as the ball stud 203 oscillates in relation to the housing 201 (refer, for example, to Japanese Unexamined Patent Publication No. 62-137408).